Circumferentially Constraining Sutures for a Stent-Graft

ABSTRACT

A circumferentially constraining suture for an endovascular prosthesis having a tubular body and a plurality of stents coupled to the tubular body includes a first thread coupled at a first end to one of the stents and a first thread loop disposed opposite the first end. The first thread extends only partially around a circumference of the tubular body in a radially expanded configuration. A second thread having a second thread loop is interlocked with the first thread loop and extends from the first thread loop around a remainder of the circumference of the tubular body. Pulling the second thread causes the first thread to circumferentially constrain the tubular body to a reduced diameter configuration. A trigger wire inserted through the first thread loop retains the first thread such that the tubular body is in the reduced diameter configuration after removal of the second thread.

RELATED APPLICATIONS

This application is a Division of and claims the benefit of U.S.application Ser. No. 13/458,076 filed Apr. 27, 2012, now allowed, thedisclosures of which are herein incorporated by reference in theirentirety.

FIELD OF THE INVENTION

This invention relates generally to endoluminal medical devices andprocedures, and more particularly to an endoluminal prosthesis orstent-graft having circumferentially constraining sutures tocircumferentially constrain the stent-graft for a partial deployment ofthe stent-graft.

BACKGROUND

Aneurysms and/or dissections may occur in blood vessels, and mosttypically occur in the aorta and peripheral arteries. Depending on theregion of the aorta involved, the aneurysm may extend into areas havingvessel bifurcations or segments of the aorta from which smaller “branch”arteries extend. Various types of aortic aneurysms may be classified onthe basis of the region of aneurysmal involvement. For example, thoracicaortic aneurysms include aneurysms present in the ascending thoracicaorta, the aortic arch, and branch arteries that emanate therefrom, suchas subclavian arteries, and also include aneurysms present in thedescending thoracic aorta and branch arteries that emanate therefrom,such as thoracic intercostal arteries and/or the suprarenal abdominalaorta and branch arteries that emanate therefrom, which could includerenal, superior mesenteric, celiac and/or intercostal arteries. Lastly,abdominal aortic aneurysms include aneurysms present in the aorta belowthe diaphragm, e.g., pararenal aorta and the branch arteries thatemanate therefrom, such as the renal arteries.

For patients with aneurysms of the aorta, surgery to replace the aortamay be performed where a portion of the aorta is replaced with a fabricsubstitute in an operation that uses a heart-lung machine. In such acase, the aneurysmal portion of the aorta is removed or opened and asubstitute lumen is sewn across the aneurysmal portion to span it. Suchsurgery is highly invasive, requires an extended recovery period and,therefore, cannot be performed on individuals in fragile health or withother contraindicative factors.

When aneurysms are near branch vessels or extend into branch vessels,stent-grafts are used with fenestrations, external couplings, or othermeans for branch stent-grafts to be deployed into the branch vessels.The location of such fenestrations or external couplings may be criticalso as not to block branch vessels. Further, when aneurysms are nearbranch vessels, the “landing zone” for the stent-graft may be limitedsuch that accurate placement of the stent-graft is critical. Thus, it isdesirable to be able to accurately position the stent-graft. However,stents of the stent-graft are normally designed to expand to a sizelarger than the target vessel to ensure apposition against the vesselwall. Thus, re-positioning the stent-graft after deployment isdifficult. It is thus desirable to partially deploy the stent-graft to adiameter larger than the delivery catheter diameter, but smaller thanthe fully deployed diameter to enable re-positioning of the stent-graft.

Further, when aneurysms are located near branch vessels, it may bedesirable to deploy the stent-graft to a diameter smaller than the fullydeployed diameter in the main vessel in order to perform various actionsto cannulate the branch vessels prior to completely deploying thestent-graft. Partially deploying the stent-graft allows for spaceoutside of the stent-graft within the main vessel to perform suchactions.

Devices to maintain stent-grafts in a partially deployed configurationafter release from a catheter have been contemplated. However, withcurrent devices, the stent-graft may jump out of position when thestent-graft is deployed. Accordingly, it would be desirable to minimizeany movement of the stent-graft when fully deploying the stent graft byreleasing the circumferentially constraining sutures.

SUMMARY OF THE INVENTION

Embodiments hereof relate to circumferentially constraining sutures fora stent-graft. The stent-graft includes a tubular body of a graftmaterial and a plurality of stents coupled to the tubular body. Thecircumferentially constraining suture in a reduced diameterconfiguration includes a first end attached to one of the stent andextending circumferentially around a complete circumference of thetubular body, with a loop of the circumferentially constraining suturedisposed opposite the first end being coupled to a trigger wireextending in a longitudinal direction along the tubular body. In adeployed configuration, the trigger wire is disengaged from the loopsuch that the stent radially expands and the circumferentiallyconstraining suture extends only partially around the circumference ofthe tubular body.

Embodiments hereof also relate to circumferentially constraining suturesfor stent-grafts. The stent-graft includes a tubular body of a graftmaterial and a plurality of stents coupled to the tubular body. Thecircumferentially constraining suture includes a first thread coupled ata first end to the tubular body or one of the stents and having a firstthread loop disposed opposite the first end, the first thread extendingonly partially around a circumference of the tubular body when thestent-graft is in a radially expanded configuration. Thecircumferentially constraining suture further includes a second threadhaving a second thread loop interlocked with the first thread loop, thesecond thread extending from the first thread loop around a remainder ofthe circumference of the tubular body. The circumferentiallyconstraining suture is configured such that pulling the second threadcauses the first thread to circumferentially constrain the tubular bodysuch that the tubular body constricts to a reduced diameterconfiguration.

Embodiments hereof also relate to a method for temporarily reducing thediameter of at least a portion of a self-expanding stent-graft. Thestent-graft includes a tubular body of a biocompatible graft materialand a plurality of self-expanding stents. A first thread having a firstthread loop and a second thread having a second thread loop areinterlocked. The first thread at a first end opposite the first threadloop is attached to one of the stents. The first thread is extendedaround a first portion of the circumference of the tubular body and thesecond thread around is extended from the first thread around a secondportion of the circumference of the tubular body. The second thread ispulled to cause the first loop of the first thread to move along thesecond portion of the circumference to reduce the diameter of thetubular body. A trigger wire is inserted longitudinally along thetubular body and through the first loop to retain the tubular body in areduced diameter configuration after the second thread is removed.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a perspective view of a main vessel stent-graft includingcircumferentially constraining sutures according to an embodimenthereof, wherein the main vessel stent-graft in radially expandedconfiguration.

FIG. 2 is a schematic illustration of a circumferentially constrainingsuture.

FIG. 2A is a schematic illustration of a circumferentially constrainingsuture.

FIG. 3 is zoomed in view of a portion of the stent-graft prosthesis ofFIG. 1 where an end of a first thread of a circumferentiallyconstraining suture is attached to a stent and an end of a second threadof the circumferentially constraining suture exits the stent.

FIGS. 3A-3C are schematic illustrations of embodiments of the first endof a first thread attached to a strut of a stent.

FIG. 4 is zoomed in view of a portion of the stent-graft of FIG. 1 wherethe first thread and the second thread are interlocked.

FIG. 5 is a schematic illustration of a circumferentially constrainingsuture of the stent-graft of FIG. 1 with the second thread pulled totighten the first thread around the stent-graft.

FIG. 6 is a schematic illustration of a trigger wire being insertedthrough a first thread loop of a circumferentially constraining suture.

FIG. 7 is a schematic illustration of the stent graft prosthesis of FIG.1 in a reduced diameter configuration with the trigger wire extendingthrough the first thread loop of each circumferentially constrainingsuture.

FIGS. 8-14 schematically illustrate a method of delivering the mainvessel stent-graft of FIG. 1 to a target site in the abdominal aorta,partial deployment of the stent-graft, and full deployment of thestent-graft after release of the circumferentially constraining sutures.

DETAILED DESCRIPTION

Specific embodiments of the present invention are now described withreference to the figures, wherein like reference numbers indicateidentical or functionally similar elements. Specific embodiments are nowdescribed with reference to the figures, wherein like reference numbersindicate identical or functionally similar elements. Unless otherwiseindicated, for the delivery system the terms “distal” and “proximal” areused in the following description with respect to a position ordirection relative to the treating clinician. “Distal” and “distally”are positions distant from or in a direction away from the clinician,and “proximal” and “proximally” are positions near or in a directiontoward the clinician. For the stent-graft prosthesis proximal is theportion nearer the heart by way of blood flow path while distal is theportion of the stent-graft further from the heart by way of blood flowpath. In addition, the term “self-expanding” is used in the followingdescription with reference to one or more stent structures of theprostheses hereof and is intended to convey that the structures areshaped or formed from a material that can be provided with a mechanicalmemory to return the structure from a compressed or constricted deliveryconfiguration to an expanded deployed configuration. Non-exhaustiveexemplary self-expanding materials include stainless steel, apseudo-elastic metal such as a nickel titanium alloy or nitinol, variouspolymers, or a so-called super alloy, which may have a base metal ofnickel, cobalt, chromium, or other metal. Mechanical memory may beimparted to a wire or stent structure by thermal treatment to achieve aspring temper in stainless steel, for example, or to set a shape memoryin a susceptible metal alloy, such as nitinol. Various polymers that canbe made to have shape memory characteristics may also be suitable foruse in embodiments hereof to include polymers such as polynorborene,trans-polyisoprene, styrene-butadiene, and polyurethane. As well polyL-D lactic copolymer, oligo caprylactone copolymer and poly cyclo-octinecan be used separately or in conjunction with other shape memorypolymers.

The following detailed description is merely exemplary in nature and isnot intended to limit the invention or the application and uses of theinvention. Although the description of the invention is in the contextof treatment of blood vessels such as aorta, the invention may also beused in any other blood vessels and body passageways where it is deemeduseful. Furthermore, there is no intention to be bound by any expressedor implied theory presented in the preceding technical field,background, brief summary or the following detailed description.

With reference to FIGS. 1-7, a self-expanding main vessel endovascularprosthesis or stent-graft 100 is configured for placement in a vesselsuch as the abdominal aorta. In the particular embodiment shown, mainvessel stent-graft 100 is a bifurcated stent-graft configured to treatshort-neck infrarenal, juxtarenal, and/or suprarenal aneurysms in a widerange of patient anatomies. However, the invention is not so limited andmay also be used for stent-grafts for use in other areas and without allof the features described below.

FIG. 1 illustrates a perspective view of main vessel stent-graft 100 ina radially expanded configuration prior to placement within a deliverycatheter. In this application, the terms “radially expandedconfiguration” and “deployed configuration” are used to describe thestent-graft when it is not in a delivery catheter and withoutcircumferentially constraining sutures (described below) restricting theexpansion of the stents of the stent-graft prosthesis. However, it wouldbe recognized by those skilled in the art that the “radially expandedconfiguration” and the “deployed configuration” may not be exactly thesame diameter because at least some of the stents of the stent-graft maybe oversized to ensure a tight seal of the stent-graft to the vesselwall. Accordingly, the “deployed configuration” may be smaller than the“radially expanded configuration” in practice due to the vessel wallrestricted expansion of the stents. However, for purposes of thisapplication, the terms generally mean that there are no outside forces(other than the vessel wall) restricting expansion of the stent-graftprosthesis. Stent-graft 100 includes a generally tubular or cylindricalgraft or body 102 that defines a lumen 107 and has a first edge or end106 and a second edge or end 108. Tubular graft 102 may be formed fromany suitable graft material, for example and not limited to, alow-porosity woven or knit polyester, DACRON material, expandedpolytetrafluoroethylene, polyurethane, silicone, ultra high molecularweight polyethylene, or other suitable materials. In another embodiment,the graft material could also be a natural material such as pericardiumor another membranous tissue such as intestinal submucosa. A pluralityof stents 104 are coupled to graft 102. Stents 104 may be coupled tograft 102 by stitching 110 or by other means known to those skilled inthe art. In the embodiment shown, stents 104 are coupled to an outsidesurface of graft 102, but stents 104 may alternatively be coupled to aninside surface of graft 102.

An anchor stent 112 is coupled to graft 102 adjacent first end 106 ofgraft 102. Anchor stent 112 is a radially-compressible ring or scaffoldthat is operable to self-expand into apposition with an interior wall ofa body vessel (not shown). Anchor stent 112 is constructed from aself-expanding or spring material, such as nitinol, and is a sinusoidalpatterned ring including a plurality of crowns or bends 113A, 113B and aplurality of struts or straight segments 115 with each crown beingformed between a pair of opposing struts. Anchor stent 112 is coupled tothe graft material so as to have a first or proximal-most set of crowns113A that extend outside of or beyond first edge 106 of graft 102 in anopen web or free-flow configuration and a second or opposing set ofcrowns 113B that is coupled to first edge 106 of tubular graft 102.Crowns 113B are coupled to tubular graft 102 by stitches or other meansknown to those of skill in the art. In the embodiment shown, crowns 113Bare coupled to an outside surface of tubular graft 102. However, crowns113B may alternatively be coupled to an inside surface of tubular graft102. Unattached or free crowns 113A may include barbs 114 for embeddinginto and anchoring into vascular tissue when stent-graft prosthesis 100is deployed in situ. In an embodiment, anchor stent 112 may be theEndurant II™ suprarenal stent, manufactured by Medtronic, Inc., ofMinneapolis, Minn.

A scallop 117 cut out or removed from graft 102 at proximal or first end106. Scallop 117 is an open-topped fenestration. When deployed in situ,scallop 117 is positioned within the aorta distal of the superiormesenteric artery (SMA) and extends around and/or frames the ostium ofthe SMA. In short-neck infrarenal, juxtarenal, and/or suprarenalaneurysms, first edge 106 of tubular graft 102 is deployed within theabdominal aorta at or near the superior mesenteric artery (SMA). Inorder to avoid blockage of blood flow into the superior mesentericartery (SMA), stent-graft 100 is positioned or oriented within theabdominal aorta such that scallop 117 is positioned around the ostium ofthe superior mesenteric artery (SMA) and the graft material of tubulargraft 102 does not occlude the ostium of the SMA. The presence ofscallop 117 for the SMA allows for main vessel stent-graft 100 to deployand seal against a sufficient length, i.e., greater than 10 mm, ofhealthy or non-aneurysmal tissue distal to the SMA for patientssuffering from short-neck infrarenal, juxtarenal, and/or suprarenalaneurysms.

A seal stent 119 is coupled to graft 102 at first end 106. Seal stent119 is configured to accommodate scallop 117. Seal stent 119 is aradially-compressible ring or scaffold that is coupled to tubular graft102 for supporting the graft material and is operable to self-expandinto apposition with an interior wall of a blood vessel (not shown).Seal stent 119 is constructed from a self-expanding or spring material,such as nitinol, and is a sinusoidal patterned ring including aplurality of crowns or bends and a plurality of struts or straightsegments with each crown being formed between a pair of opposing struts.Seal stent 119 is coupled to tubular graft 102, immediately distal offirst end 106 thereof and distal of anchor stent 112. Seal stent 119 iscoupled to tubular graft 102 by stitches or other means known to thoseof skill in the art. In the embodiment shown, seal stent 119 is coupledto an outside surface of tubular graft 102, but seal stent 119 mayalternatively be coupled to an inside surface of tubular graft 102. Sealstent 119 includes at least two struts that are lengthened or elongatedwith respect to the remaining struts to accommodate scallop 117.

In the embodiment shown, stent-graft 100 includes a first tubular leg orextension 116 and a second tubular leg or extension 118, each extendingfrom second end 108. Legs 116, 118 define lumens that are in fluidcommunication with lumen 107 of tubular graft 102. In an embodiment,legs 116, 118 are integrally formed with tubular graft 102 as a unitarygraft component and thus are formed from the same material as tubulargraft 102. In another embodiment, legs 116, 118 may be formed separatelyfrom tubular graft 102 and coupled thereto. In the embodiment shown,legs 116, 118 are of equal length and are oriented anterior andposterior within the abdominal aorta when deployed in the abdominalaorta.

Stent-graft 100 also includes couplings 120, 122 for connectingstent-graft 100 to branch vessel prostheses (not shown) to accommodatethe left and right renal arteries, respectively. Tubular graft 102includes opposing fenestrations or openings formed through a sidewall ofthe graft material. Couplings 120, 122 are disposed on an outsidesurface of main vessel stent-graft 100 corresponding to openings intubular graft 102. Couplings 120, 122 may be generally cylindricallyshaped or frustoconically shaped. Couplings 120, 122 include couplinggraft material. The graft material of couplings 120, 122 may be the sametype of graft material as the graft material of tubular graft 102 or itmay be a different material. Also, in the embodiment shown, couplings120, 122 are separate components that are attached to tubular graft 102.However, it would be understood by those of ordinary skill in the artthat couplings 120, 122 may be formed as a continuation of tubular graft102. Couplings 120, 122 include self-expanding support stents orsinusoidal rings 124, 126, respectively, coupled to the coupling graftmaterial. Support stents 124, 126 are constructed from a self-expandingor spring material, such as nitinol, and is a sinusoidal patterned ringincluding a plurality of crowns or bends and a plurality of struts orstraight segments with each crown being formed between a pair ofopposing struts. In an embodiment, support stents 124, 126 are four peakstents and thus include eight crowns, although it will be apparent toone of ordinary skill in the art that the support stent may include moreor less crowns. Other embodiments of couplings 124, 126 may be used aswould be understood by those skilled in the art.

Although stent-graft 100 has been described generally above, moredetails of stent-graft 100 may be found in U.S. patent application Ser.Nos. 13/458,209 and 13/458,242 to Coghlan et al., filed Apr. 27, 2012(now published as U.S. Pub. Nos. 2013/0289701 A1 and 2013/0289702 A1),herein incorporated by reference in their entirety. Further, althoughstent-graft 100 has been described with the particular featuresdescribed above, the circumferentially constraining sutures describedbelow may be used with any stent-graft where it is desirable to have astaged deployment of the stent-graft prosthesis.

As described above, FIG. 1 shows stent-graft 100 in a radially expandedconfiguration prior to placement within a delivery catheter for deliveryto a treatment site. In the embodiment shown, five circumferentiallyconstraining sutures 130 are disposed around stent-graft 100.Circumferentially constraining sutures 130, when utilized as describedin more detail below, reduce the diameter of stent-graft prosthesis 100by about 40 to 70 percent from the radially expanded configuration.However, stent-graft 100 in the reduced diameter configuration has adiameter about 40 to 50 percent larger than in a delivery configurationwherein stent-graft 100 is disposed within a sleeve of a deliverycatheter. Those of ordinary skill in the art would recognize that byadjusting the length of the threads of the circumferentiallyconstraining sutures, as described in more detail below, the reductionin the diameter of stent-graft prosthesis by the circumferentiallyconstraining sutures may be varied outside of the ranges noted above.

In the embodiment shown, circumferentially constraining sutures 130 aredisposed around the graft material of tubular graft 102 adjacent five ofstents 104. As explained in more detail below, anchor stent 112 is heldby a tip capture mechanism during delivery and partial deployment ofstent-graft 100. The tip capture mechanism holds proximal-most crowns113A of anchor stent 112 in a reduced diameter configuration afterretraction of the outer sheath or sleeve covering stent-graft 100, asknown to those skilled in the art. Thus, anchor stent 112 and seal stent119 do not include circumferentially constraining sutures because theydo not fully deploy due to the tip capture mechanism. However, as wouldbe understood by those skilled in the art, more or lesscircumferentially constraining sutures 130 may be utilized depending onthe number of stents 104 coupled to tubular graft 102, the particularapplication and procedure, and the locations where it is desirable tohave a reduced diameter.

Each circumferentially constraining suture 130 comprises a first threador string 132 interlocked with a second thread or string 134 atinterlocking location 140. First thread 132 is formed into a firstthread loop 136 by having a first end 146 and a second end 147 of firstthread 132 disposed tied to each other at knot 137, as shown in FIG. 2.Essentially, first thread 132 is folded back at approximately amid-point thereof to form a first thread loop 136. First thread 132 hasa first thread length FL that is less than the circumference ofstent-graft 100. In particular, first thread length FL may be between30% and 60% of the circumference of stent-graft 100. Similarly, secondthread 134 is folded back at approximately a mid-point thereof to form asecond thread loop 138, as shown in FIG. 2. As explained above, firstthread length FL may be shorter to make the reduced diameter smaller andfirst thread length FL may be longer to make the reduced diameterlarger. First thread loop 136 and second thread loop 138 are interlockedwith each other at 140 as shown in FIG. 2. As also shown in FIG. 2, ends142 and 143 of second thread 134 disposed opposite second thread loop138 are tied or otherwise attached to a pull tab 144. Pull tab 144 asshown is a circular, donut shaped tab with ends 142, 143 of secondthread 134 tied to pull tab 144. However, those of ordinary skill in theart would recognize that other pull tabs may be used, or a large knottied in ends 142, 143 may function as a pull tab. Further, those ofordinary skill in the art would recognize that other ways of formingfirst and second threads with interlocked first and second thread loopsmay be used. For example, and not by way of limitation, FIG. 2A showsfirst end 246 of first thread 232 that may be attached to strut 105 (seeFIG. 3C described below), and second end 247 may form a first threadloop 232 by forming a loop and tying second end 247 to first thread 232and 245. Similarly, one end 242 of second thread 234 may be tied to pulltab 244 and the other end 243 of second thread 234 may form a loop 238and be tied to second thread 234 at 245. Other ways of forming first andsecond thread loops may be used, as known to those skilled in the art.First thread 132, 232 and second thread 134, 234 may be monofilament orbraided and formed of polyester, ultra high molecular weightpolyethelene (UHMWPE), polypropylene, or other alternate threadmaterials known to those skilled in the art.

In the embodiment shown, first and second ends 146, 147 of first thread132 are tied to each other to form first thread loop 136, and firstthread loop 136 is tied to a strut 105 of a stent 104, as shown indetail in FIG. 3A. First thread 132 then extends between stent 104 andthe graft material of body 102, as shown in FIGS. 3 and 4. First thread132 also extends between stitches 110 which attach stent 104 to thegraft material of body 102, thereby keeping first thread 132 from movinglongitudinally along stent-graft prosthesis 100. First thread 132 isinterlocked with second thread 134, which also extends circumferentiallyaround graft material 102 between the graft material and stent 104, asshown in FIG. 4. Other ways of forming first thread loop 136 and ofattaching first thread loop 136 to stent 104 may be utilized, as wouldbe recognized by those skilled in the art. For example, and not by wayof limitation, ends 146, 147 of first thread 132 may be tied to eachother around strut 105, as shown in FIG. 3B. Further, using the firstthread loop 234 shown in FIG. 2A, first end 246 of first thread may betied around strut 105 at knot 248 and first thread loop 236 is disposedat the opposite end of knot 248 by having second end 247 form loop 236and then tying second end 247 to first thread 232, as shown in FIG. 3C.

Circumferentially constraining sutures 130 function to circumferentiallyconstrain stent-graft 100, as will be described with reference to FIGS.5-7. First, as shown in FIG. 5, second thread 134 is pulled by pullingon pull tab 144. Because first thread 132 is attached to a body stent104 at an end opposite first thread loop 136, and second thread 134 isdisposed between graft 102 and stents 104, pulling second thread 134causes first thread to continue around the circumference of stent-graft100, following the path of second thread 134 until the location wherepull tab 144 was initially located. At that point, pulling second thread134 causes first thread to continue following second thread 134, butfirst thread loop 136 may extend radially away from stent-graft 100, asshown in FIG. 5. Further, because first thread 132 is fixed to a stent104 at 148, pulling second thread 134 and first thread 132 along with itcauses first thread 132 to circumferentially close or tighten or shrinkstent-graft 100 in the area of circumferentially constraining suture130, as also shown in FIG. 5.

Next, as shown in FIG. 6, a release or trigger wire 150 extendinggenerally longitudinally along stent-graft 100 is inserted through firstthread loop 136. The steps of FIGS. 5 and 6 are repeated for eachcircumferentially constraining suture 130 of stent-graft 100.Preferably, the same trigger wire 150 is used for all thecircumferentially constraining sutures, but it is not necessary.Although FIGS. 5 and 6 show the middle circumferentially constrainingsuture 130, it would be understood that with a single trigger wire 150,it is preferable to proceed from either the proximal-most or thedistal-most circumferentially constraining suture 130 and proceed eitherdistally or proximally, respectively, with trigger wire 150 advancingalong either distally or proximally, respectively, to engage each firstthread loop 136 of each first thread 132.

When each first thread loop 136 of each first thread 132 is engaged bytrigger wire 150, each second thread 134 may be removed. This causes thestent 104 associated with the circumferentially constraining suture totry to expand to its radially expanded diameter. However, becausetrigger wire 150 holds first threaded loop 136 at the location wheresecond thread 134 exited from between graft 102 and the stent 104, andthe first thread length FL of first thread 132 is fixed and is less thanthe circumference of stent-graft 100, trigger wire 150 holds stent-graft100 in a reduced diameter configuration. It is preferable that pull tab144 is located adjacent knot 148, as shown in FIG. 3. In other words, itis preferable that when trigger wire 150 holds circumferentiallyconstraining suture 130 such that stent-graft 100 is in the reduceddiameter configuration, first thread 132 extends completely around thecircumference of stent-graft 100. In such an embodiment, the firstthread length FL of first thread 132 determines the amount that thecircumferentially constraining suture 130 reduces the diameter ofstent-graft 100. Further, in such an embodiment, the circumferentiallyconstraining suture 130 constrains stent-graft 100 around the entirecircumference of stent-graft 100, thereby applying equal restrainingforce around the circumference of the stent-graft to minimize movementof the stent-graft when releasing stent graft prosthesis 100 from thecircumferentially constraining sutures 130 by removing the trigger wire150.

After the trigger wire 150 is disposed through first thread loop 136 ofeach circumferentially constraining suture 130, second thread 134 can beremoved such as by cutting second thread loop 138. This leavesstent-graft 100 in the reduced diameter configuration with trigger wire150 disposed through each first thread loop 136 of each first thread 132of each circumferentially constraining suture 130, as shown in FIG. 7.Trigger wire 150 extends within a delivery catheter to a handle of thedelivery catheter such that a user may pull trigger wire 150 to releaseeach circumferentially constraining suture 130 such that stent-graftprosthesis 100 may expand to its deployed configuration, as described inmore detail below. Trigger wire 150 may be any suitable wire formed ofany suitable material. For example, and not by way of limitation,trigger wire may be formed of nitinol, and may have a diameter in therange of 0.010 to 0.014 inch. However, it is understood that differentmaterials and different sizes can be used provided that the trigger wirecan perform the functions described herein of holding first thread 132to maintain the stent-graft in a reduced diameter configuration and ofreleasing the circumferentially constraining suture by retraction of thetrigger wire without excessive force by the user.

Stent-graft 100 can then be disposed within a delivery catheter as knownto those skilled in the art. After delivery to a target site and partialdeployment of stent-graft prosthesis 100 from a sheath or outer cover ofthe delivery system, trigger wire 150 may be retracting proximally(i.e., towards the clinician) to release circumferentially constrainingsutures 130 and allow stent-graft prosthesis 100 to fully deploy to itsradially expanded or deployed configuration, as described in more detailbelow. With second thread 134 removed from each circumferentiallyconstraining suture 130, only first thread 132 remains. The drawings anddescription regarding delivery and deployment of the stent-graft 100 mayrefer to first thread 132 and circumferentially constraining suture 130interchangeably.

FIG. 8 shows a main vessel delivery system 882, with main vesselstent-graft 100 compressed therein, advanced over a main vessel guidewire 884 and to the target site in the abdominal aorta A. Guide wire 884is typically inserted into the femoral artery and routed up through theleft iliac artery LI to abdominal aorta, as is known in the art. FIGS.8-14 show a posterior view of the aorta A and the vessels that branchtherefrom. Accordingly, the superior mesenteric artery (SMA), forexample, is shown exiting the anterior side of the aorta opposite theposterior side shown in the drawings, and is therefore shown in phantomwhere blocked by the aorta. FIGS. 8-14 show similar devices as thoseshown and described in co-pending U.S. patent application Ser. Nos.13/457,535 and 13/457,544 to Maggard et al., filed Apr. 27, 2012 (nowpublished as U.S. Pat. Pub. Nos. 2013/0289696 A1 and 2013/0289693 A1,respectively); U.S. patent application Ser. Nos. 13/457,537 and13/457,541 to Argentine et al., filed Apr. 27, 2012 (now published asU.S. Pat. Pub Nos. 2013/0289691 A1 and 2013/0289692 1, respectively);and U.S. patent application Ser. Nos. 13/458,209 and 13/458,242 toCoghlan et al., filed Apr. 27, 2012 (now published as U.S. Pat. Pub.Nos. 2013/0289701 A1 and 2013/0289702 A1), herein incorporated byreference in their entirety. However, in the above-identifiedapplications, the views of the delivery and deployment of thestent-graft prosthesis are anterior views of the aorta. Delivery system882 is fully described in co-pending U.S. patent application Ser. Nos.13/457,535 and 13/457,544 to Maggard et al., filed Apr. 27, 2012 (nowpublished as U.S. Pat. Pub. Nos. 2013/0289696 A1 and 2013/0289693 A1,respectively); and U.S. patent application Ser. Nos. 13/457,537 and13/457,541 to Argentine et al., filed Apr. 27, 2012 (now published asU.S. Pat. Pub. Nos. 2013/0289691 A1 and 2013/0289692 A1, respectively),herein incorporated by reference in their entirety. Main vesselstent-graft prosthesis 100 is mounted on a catheter shaft 988 (see FIG.9) of the delivery system and an outer delivery sheath 886 of thedelivery system covers and restrains main vessel stent-graft prosthesis100 in a radially compressed delivery configuration for deliverythereof. As will be understood by those of ordinary skill in the art,delivery system 882 may include a tip capture mechanism (not shown)which engages the proximal-most set of crowns of anchor stent 112 untilretraction of the tip capture mechanism releases the proximal-most setof crowns for final deployment of main vessel stent-graft prosthesis100.

FIG. 9 illustrates a first or initial step to deploy main vesselstent-graft prosthesis 100 in which outer delivery sheath 886 ofdelivery system 882 is retracted to release or uncover a proximal endportion of main vessel stent-graft prosthesis 100. When first releasedfrom the delivery system, the proximal end portion may be positionedsuch that scallop 117 (not shown in FIG. 9) is below the target site ofthe superior mesenteric artery (SMA). The proximal-most set of crowns ofanchor stent 112 is captured or restrained by the tip capture mechanismof delivery system 882. Delivery sheath 886 is retracted to expose atleast seal stent 119. In the embodiment of FIG. 9, delivery sheath 886is shown as retracted to expose a body stent 104.

As described in co-pending U.S. patent application Ser. Nos. 13/457,535and 13/457,544 to Maggard et al., filed Apr. 27, 2012 (now published asU.S. Pat. Pub. Nos. 2013/0289696 A1 and 2013/0289693 A1, respectively);U.S. patent application Ser. Nos. 13/457,537 and 13/457,541 to Argentineet al., filed Apr. 27, 2012 (now published as U.S. Pat. Pub. Nos.2013/0289691 and 2013/0289692 A1, respectively); and U.S. patentapplication Ser. Nos. 13/458,209 and 13/458,242 to Coghlan et al., filedApr. 27, 2012 (now published as U.S. Pat. Pub. Nos. 2013/0289701 A1 and2013/0289702 A1), previously incorporated by reference in theirentirety, the superior mesenteric artery (SMA) is cannulated and themain vessel stent-graft 100 is repositioned to align scallop 117 withthe superior mesenteric artery (SMA). The terms “cannulation” and“cannulate” are used herein with reference to the navigation of aguidewire and guide catheter into a target vessel.

With the proximal end portion of main vessel stent-graft 100 nowpositioned as desired, delivery sheath 886 is shown retracted in FIG. 10to expose at least couplings 120, 122 of main vessel stent-graftprosthesis 100. Anchor stent 112 is still captured or restrained by thetip capture mechanism of delivery system 882 such that the proximal endportion of stent-graft 100 does not fully deploy. Further, first threads132 of circumferentially constraining sutures 130 prevent thestent-graft prosthesis 100 from fully deploying in the areas that havebeen released from sheath 886. These areas radially expand from thedelivery configuration to a reduced diameter configuration that isradially larger than the delivery configuration but 30 to 60% smaller indiameter than the deployed configuration, as explained above.

The renal arteries, right renal artery RR and left renal artery LR, arethen cannulated, as described in co-pending U.S. patent application Ser.Nos. 13/457,535 and 13/457,544 to Maggard et al., filed Apr. 27, 2012(now published as U.S. Pat. Pub. Nos. 2013/0289696 A1 and 2013/0289693A1, respectively); U.S. patent application Ser. Nos. 13/457,537 and13/457,541 to Argentine et al., filed Apr. 27, 2012 (now published asU.S. Pat. Pub. Nos. 2013/0289691 A1 and 2013/0289692 A1, respectively);and U.S. patent application Ser. Nos. 13/458,209 and 13/458,242 toCoghlan et al., filed Apr. 27, 2012 (now published as U.S. Pat. Pub.Nos. 2013/0289701 A1 and 2013/0289702 A1), previously incorporated byreference in their entirety. The renal arteries are cannulated whilesheath 886 is partially retracted as shown in FIG. 10. After the renalarteries have been cannulated, the sheath 886 is fully retracted torelease stent-graft 100 from sheath 886 and the branch vessel prosthesisdelivery systems are advanced into the renal arteries. This leaves mainvessel stent-graft 100 partially deployed in a reduced diameterconfiguration due to first threads of circumferentially constrainingsutures 130, as shown in FIG. 11.

Trigger wire 150 is then retracted proximally (i.e. towards thephysician), as shown by the arrow in FIG. 12. As trigger wire 150 movespast stents 104A and 104B, first threads 132A and 132B ofcircumferentially constraining sutures are released, allowing thatportion of stent-graft 100 to expand to the deployed configuration.First threads 132A, 132B remain attached at one end to stents 104A,104B, respectively, as described above and shown at 148A, and firstthreads 132A, 130B extend between graft 102 and stents 104A, 104B.Because first threads 132A and 132B are each shorter than thecircumference of the deployed stent-graft prosthesis 100, each firstthread 132A, 132B extends only partially around the circumference ofstent-graft prosthesis 100. Further, since first thread loop 136 (notshown in FIG. 12) of first threads 132A, 132B is not attached to triggerwire 150 or any portion of stent-graft prosthesis 100, first and secondthreads 132A, 132B do not exert a radial force to constrain stent-graft100 in a reduced diameter configuration. As trigger wire 150 continuesto be retracted proximally, the remaining first threads 132C, 132D, 132Eof the respective circumferentially constraining sutures 130 arereleased, thereby allowing stent-graft 100 to fully deploy, as shown inFIG. 13. In addition, anchor stent 112 may be released from the tipcapture mechanism of the delivery system 882, as also shown in FIG. 13.When anchor stent 112 is released from delivery system 882, seal stent119 fully expands and conformingly engages and seals the edges ofscallop 117 with the blood vessel inner wall. Trigger wire 150 forcircumferentially constraining sutures 130 may also be used as a capturemechanism (not shown) as described in co-pending U.S. patent applicationSer. Nos. 13/457,535 and 13/457,544 to Maggard et al., filed Apr. 27,2012 (now published as U.S. Pat. Pub. Nos. 2013/0289696 A1 and2013/0289693 A1, respectively); and U.S. patent application Ser. Nos.13/457,537 and 13/457,541 to Argentine et al., filed Apr. 27, 2012 (nowpublished as U.S. Pat. Pub. Nos. 2013/0289691 A1 and 2013/0289692 A1,respectively), previously incorporated by reference herein in theirentirety.

The branch vessel stent-graft prostheses may then be deployed withinright renal artery RR and left renal artery LR, respectively, byretracting outer sheaths of the branch vessel stent-graft deliverysystems, as known to those skilled in the art and described inco-pending U.S. patent application Ser. Nos. 13/457,535 and 13/457,544to Maggard et al., filed Apr. 27, 2012 (now published as U.S. Pat. Pub.Nos. 2013/0289696 A1 and 2013/0289693 A1, respectively); U.S. patentapplication Nos. 13/457,537 and 13/457,541 to Argentine et al., filedApr. 27, 2012 (now published as U.S. Pat. Pub. Nos. 2013/0289691 A1 and2013/0289692 A1, respectively); and U.S. patent application Ser. Nos.13/458,209 and 13/458,242 to Coghlan et al., filed Apr. 27, 2012 (nowpublished as U.S. Pat. Pub. Nos. 2013/0289701 A1 and 2013/0289702 A1),previously incorporated by reference in their entirety. Further, limbprostheses may be delivered and deployed within legs 116, 118 of mainvessel stent-graft prosthesis 100, extending into right iliac artery RIand left iliac artery LI, respectively, as shown in FIG. 14. All thedelivery systems are removed, leaving the main vessel stent-graft 100,the branch vessel prostheses, and the limb prostheses, as shown in FIG.14.

While various embodiments according to the present invention have beendescribed above, it should be understood that they have been presentedby way of illustration and example only, and not limitation. It will beapparent to persons skilled in the relevant art that various changes inform and detail can be made therein without departing from the spiritand scope of the invention. It will also be understood that each featureof each embodiment discussed herein, and of each reference cited herein,can be used in combination with the features of any other embodiment.All patents and publications discussed herein are incorporated byreference herein in their entirety.

1-13. (canceled)
 14. A method of temporarily reducing the diameter of at least a portion of a self-expanding endovascular prosthesis, the prosthesis comprising a tubular body of a biocompatible graft material and a plurality of self-expanding stents, the method comprising the steps of: interlocking a first thread having a first thread loop with a second thread having a second thread loop; attaching the first thread at a first end opposite the first thread loop to the tubular body; extending the first thread around a first portion of a circumference of the tubular body and the second thread around a second portion of the circumference of the tubular body; pulling the second thread to cause the first loop of the first thread to move along the second portion of the circumference to reduce the diameter of the tubular body; and inserting a trigger wire through the first thread loop.
 15. The method of claim 14, further comprising the step of removing the second thread after the trigger wire is inserted through the first thread loop.
 16. The method of claim 14, wherein the step of attaching the first end of the first thread loop to the tubular body comprises tying the first thread to one of the stents.
 17. The method of claim 14, wherein the step of attached the first end of the first thread loop to the tubular body comprises tying the first end to a strut of one of the stents.
 18. The method of claim 14, wherein the step of attaching the first end of the first thread loop to the tubular body comprises wrapping a portion of the first thread loop around a strut of the stent and pulling the remainder of the of the first thread loop through the portion of the first thread loop wrapped around the strut.
 19. The method of claim 14, wherein the second thread includes a pull tab disposed at a first end of the second thread opposite the second thread loop and where the step of pulling the second thread comprises pulling the pull tab.
 20. The method of claim 14, wherein the step of inserting the trigger wire through the first thread loop comprises inserting the trigger wire in a longitudinal direction relative to the tubular body. 